Internal-combustion engine



April 1930- E. BECKER 1,753,196

INTERNAL COMBUSTION ENGINE Filed April 17, 1928 Patented Apr. 8, 1930 UNITED STATES PATENT OFFICE ERNST BECKER, OF BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR TO SIEMENS & HALSKE, AKTIENGESELLSCHAFT, OF SIEMENSSTADT, NEAR BERLIN, GERMANY, A

CORPORATION OF GERMANY INTERNAL-COMBUSTION ENGINE Application filed April 17, 1928, Serial No.

My invention relates to improvements in internal combustion engines.

It is already known to construct crankshafts in such a manner that the crank-pin may be detached from the crank-arm, for the purpose of allowing bearing rings or ball-races and the like to be placed in position upon the pin. Joints of this kind are generally constructed in such a way that the end of the crank-pin is tapered and forced or drawn into a correspondingly tapering bore of the crank-arm by means of a screw.

There are also known arrangements in which the crank-arm is provided with a split recess or bore, which is provided with a large number of key-like projections uniformly spaced around the entire circumference. These projections engage. correspondingly shaped grooves or keyways in the crank-pin and prevent the pin from rotation. while the attachment of the pin is effected by clamping the split crank-arm. In this latter arrangement a good fit at the sides of the. keys is attained at those fitting keys only. which are disposed atthe curvature located diametrically opposite the slit.

According to my invention the crank-arm is provided with a recess or bore. which shows only two fitting key-like projections arranged symmetrically to the axis and at an angle of 120 apart.

An embodiment of my invention is illustrated by way of example in the drawings affixed hereto and forming part of my invention.

In these drawings:

Fig. 1, represents an internal combustion engine in sectional elevation, to which my invention is applied,

Fig. 2, the improved crank-arm in frontelevation, and in larger scale.

Fig. 3, the crank-arm of Fig. 2 in partly sectional side elevation, and

Fig. 4, the pertaining crank-pin together with its other crank-arm in side elevation.

Referring to the drawings it will be seen that the crank-shaft 9 is journaled at the points 13 in the engine casing. The connecting rod 12 engages the crank-pint which is located between the two crank-arms 1 and 11.

270,694, and in Germany April 27, 1927.

The cranksarm 1 contains'a boring 2 provided with an axially extending slit 8. At the semicircle; opposite this slit, the boring is provided with two projections 4 acting as keys and which are spaced apart by 120 and are located symmetrically to the axis. This arrangement has the advantage that the keys 4 are thus located. at that part of the curvature of the boring, which is least interfered with by the deformation which occurs when the ends of the split crank-arm are drawn together. The end of the crank-pin 6 entering the bore of the crank-arm 'is provided with grooves 5 fitting the keys 4, and which may be produced in the usual manner by planing or millin During the assembly the crank-pin 6 is introduced into the boring 2 -of the crank arm 1 and the ends of the arm are then drawn together by a bolt threaded into the tapped bore 8. By this clamping processthe upper portions of the crank-arm are firmly pressed against the pin.

In this way a joint between the crank-pin and the cranloarm is obtained which closely fits all along the circumference and which combines great durability with ease and cheapness of production. It has the further advantage that it is easily detachable and yet offers absolute security against the turning of the pin within the crank. It is not absolutely necessary, that the crank-pin should be detachably joined to both crank-arms. it may equally well be integral with one arm of the crank or be attached to it in any other suitable manner.

In producing the boring 2 the crank-arm 1 is according to the invention first provided with a bore of smaller diameter corresponding with the thickness of the projections 4. The material between the projections is then cut away in any suitable manner, preferably with a broach. Since, however, a broiching pin with only two recesses at 120 apart would not ensure a uniform guidance, a broach is preferably employgd the profile of which shows recesses for three projections spaced by 120. The third ofthe projections 7 thus obtainedis shown in broken lines in Fig. 1. Since the remainder of this projection after the milling of the slot would not ensure a reliable fit owing to the deformation when ing key ways adapted to engage said keys, the arm end is clamped together,-this remainand means for clamping the split arm porder is cut away after the completion of the tiontogetherr 1 a r broaching operation. i 1 a In testimony whereof I aflix my signature. Various modifications and changes may be p ERNST BECKER.

made without departing from .thespirit and i the scope of the invention, and I desire, there- V fore, that only such limitations shall be placed thereonas are imposed by the prior art.

I claim as my invention 75 1. A'divided crank-shaft having at least a one end of its crank-pin a detachable connection with the pertaining crank-arm, said connection comprising a boss at said pin end,

I said crank-arm having a boring adapted to I 80 receive said boss and being split open at one point of said boring in axial direction thereof, and two axially directed key way connections between said boss and said crank-arm boring,ispaced substantially 120 apart, and

being symmetrically disposed opposite the l split portion of said crank-arm, and means for clamping the split arm portion together.

2. A divided crank-shaft having at least .7 25 at one end of its crank-pin a detachable conr nection with the pertaining crank-arm, said connection comprising a boss at said pin end, said crank-arm having a boring adapted to receive said boss and being split open at one 30 point of said boring in axial direction therer of, said boring having two axially directed keys protruding from its periphery and being integral with the crank-arm, said keys being spaced apart substantially 120 and v 35 being symmetrically disposed opposite the split portion of the crank-arm, said boss having two corresponding key ways adapted to engage said keys, and means for clamping the split arm portion together..

0 3. A divided crank-shaft having at least v at one end of its crank-pin a detachable con-' nection with the pertaining crank-arm, said connection comprising a boss at said pin end, said crank-arm having a boring adapted to 45 'receive'said boss and being split at its end in 1 no axial direction of said boring, and two axially directed key way connections between said boss and said crank-arm boring, spaced substantially 120 apart, and being symmet- 0 rically disposed opposite the split portion of said crank-arm, and means for clamping the split arm portion together. i

4. A divided crank-shaft having at least atone end of its crank-pin a detachable con- 65 nection with the pertaining crank-arm, said connection comprising a boss at said pin end,

said crank-arm having a boring adapted to receive said boss and being split at its end in axlal d rection of said boring, sald boring 60 having two axially directed keys protruding from its peripmry and being integral with the crank-arm, said keys being spaced apart substantially 120 and being symmetrically disposed opposite the split portion of the U crank-arm, said boss having two correspond- 

